1. Field of the Invention
The present invention relates to a refrigerator and in particular relates to a Stirling refrigerator including a regenerator.
2. Description of the Related Art
There are available many types of cryogenic refrigerators that produce cryogenic temperatures. One of such cryogenic refrigerators is a Stirling refrigerator. As compared with other cryogenic refrigerators such as a Gifford-MacMahon (GM) refrigerator, the Stirling refrigerator has a feature where the downsizing is easier. Similar to the GM refrigerator, a natural medium such as helium gas or the like is used as a working gas and therefore the Stirling refrigerator is an environmentally-friendly cryocooler.